fix for got an unexpected keyword argument 'num_pools'
fix for got an unexpected keyword argument 'num_pools'

requests's HTTPAdapter API is pool_connections for number of connection of the pool

Signed-off-by: Pierre Tardy <6ce6e27ffdda0dd0ca69681951e519022e43f284@gmail.com>

auready/docker-py,vpetersson/docker-py,kaiyou/docker-py,docker/docker-py,funkyfuture/docker-py,kaiyou/docker-py,vdemeester/docker-py,youhong316/docker-py,docker/docker-py,vdemeester/docker-py,funkyfuture/docker-py,bfirsh/docker-py,bfirsh/docker-py,dimaspivak/docker-py,youhong316/docker-py,dimaspivak/docker-py,vpetersson/docker-py,auready/docker-py